| 0,0 → 1,382 |
|---|
| Author: Magnus Holmgren <holmgren@debian.org> |
| Description: Check keys against openssh-blacklist |
| Check keys before accepting for pubkey authentication as well as on conversion |
| by lsh-writekey and lsh-decode-key. |
| . |
| blacklist.c code copied from the openssh package and adapted for LSH. |
| |
| --- a/src/Makefile.am |
| +++ b/src/Makefile.am |
| @@ -69,7 +69,8 @@ liblsh_a_SOURCES = abstract_io.c abstrac |
| unix_interact.c unix_process.c unix_random.c unix_user.c \ |
| userauth.c \ |
| werror.c write_buffer.c write_packet.c \ |
| - xalloc.c xauth.c zlib.c |
| + xalloc.c xauth.c zlib.c \ |
| + blacklist.c |
| |
| liblsh_a_LIBADD = @LIBOBJS@ |
| |
| --- a/src/abstract_crypto.h |
| +++ b/src/abstract_crypto.h |
| @@ -162,7 +162,9 @@ MAC_DIGEST((instance), lsh_string_alloc( |
| (public_key method (string)) |
| |
| ; Returns (public-key (<pub-sig-alg-id> <s-expr>*)) |
| - (public_spki_key method (string) "int transport"))) |
| + (public_spki_key method (string) "int transport") |
| + |
| + (key_size method uint32_t))) |
| */ |
| |
| #define VERIFY(verifier, algorithm, length, data, slength, sdata) \ |
| @@ -170,7 +172,7 @@ MAC_DIGEST((instance), lsh_string_alloc( |
| |
| #define PUBLIC_KEY(verifier) ((verifier)->public_key((verifier))) |
| #define PUBLIC_SPKI_KEY(verifier, t) ((verifier)->public_spki_key((verifier), (t))) |
| - |
| +#define KEY_SIZE(verifier) ((verifier)->key_size((verifier))) |
| |
| /* GABA: |
| (class |
| --- a/src/abstract_crypto.h.x |
| +++ b/src/abstract_crypto.h.x |
| @@ -161,6 +161,7 @@ struct verifier |
| int (*(verify))(struct verifier *self,int algorithm,uint32_t length,const uint8_t *data,uint32_t signature_length,const uint8_t *signature_data); |
| struct lsh_string *(*(public_key))(struct verifier *self); |
| struct lsh_string *(*(public_spki_key))(struct verifier *self,int transport); |
| + uint32_t *(*(key_size))(struct verifier *self); |
| }; |
| extern struct lsh_class verifier_class; |
| #endif /* !GABA_DEFINE */ |
| --- /dev/null |
| +++ b/src/blacklist.c |
| @@ -0,0 +1,152 @@ |
| +#if HAVE_CONFIG_H |
| +#include "config.h" |
| +#endif |
| + |
| +#include <assert.h> |
| + |
| +#include "atoms.h" |
| +#include "format.h" |
| +#include "lsh_string.h" |
| +#include "werror.h" |
| +#include "crypto.h" |
| + |
| +#include <sys/types.h> |
| +#include <sys/stat.h> |
| +#include <unistd.h> |
| +#include <fcntl.h> |
| +#include <string.h> |
| + |
| +int blacklisted_key(struct verifier *v, int method); |
| + |
| +/* Scan a blacklist of known-vulnerable keys in blacklist_file. */ |
| +static int |
| +blacklisted_key_in_file(struct lsh_string *lsh_hash, struct lsh_string *blacklist_file) |
| +{ |
| + int fd = -1; |
| + const char *hash = 0; |
| + uint32_t line_len; |
| + struct stat st; |
| + char buf[256]; |
| + off_t start, lower, upper; |
| + int ret = 0; |
| + |
| + debug("Checking blacklist file %S\n", blacklist_file); |
| + fd = open(lsh_get_cstring(blacklist_file), O_RDONLY); |
| + if (fd < 0) { |
| + ret = -1; |
| + goto out; |
| + } |
| + |
| + hash = lsh_get_cstring(lsh_hash) + 12; |
| + line_len = strlen(hash); |
| + if (line_len != 20) |
| + goto out; |
| + |
| + /* Skip leading comments */ |
| + start = 0; |
| + for (;;) { |
| + ssize_t r; |
| + char *newline; |
| + |
| + r = read(fd, buf, sizeof(buf)); |
| + if (r <= 0) |
| + goto out; |
| + if (buf[0] != '#') |
| + break; |
| + |
| + newline = memchr(buf, '\n', sizeof(buf)); |
| + if (!newline) |
| + goto out; |
| + start += newline + 1 - buf; |
| + if (lseek(fd, start, SEEK_SET) < 0) |
| + goto out; |
| + } |
| + |
| + /* Initialise binary search record numbers */ |
| + if (fstat(fd, &st) < 0) |
| + goto out; |
| + lower = 0; |
| + upper = (st.st_size - start) / (line_len + 1); |
| + |
| + while (lower != upper) { |
| + off_t cur; |
| + int cmp; |
| + |
| + cur = lower + (upper - lower) / 2; |
| + |
| + /* Read this line and compare to digest; this is |
| + * overflow-safe since cur < max(off_t) / (line_len + 1) */ |
| + if (lseek(fd, start + cur * (line_len + 1), SEEK_SET) < 0) |
| + break; |
| + if (read(fd, buf, line_len) != line_len) |
| + break; |
| + cmp = memcmp(buf, hash, line_len); |
| + if (cmp < 0) { |
| + if (cur == lower) |
| + break; |
| + lower = cur; |
| + } else if (cmp > 0) { |
| + if (cur == upper) |
| + break; |
| + upper = cur; |
| + } else { |
| + ret = 1; |
| + break; |
| + } |
| + } |
| + |
| +out: |
| + if (fd >= 0) |
| + close(fd); |
| + return ret; |
| +} |
| + |
| +/* |
| + * Scan blacklists of known-vulnerable keys. If a vulnerable key is found, |
| + * its fingerprint is returned in *fp, unless fp is NULL. |
| + */ |
| +int |
| +blacklisted_key(struct verifier *v, int method) |
| +{ |
| + const char *keytype; |
| + int ret = -1; |
| + const char *paths[] = { "/usr/share/ssh/blacklist", "/etc/ssh/blacklist", NULL }; |
| + const char **pp; |
| + struct lsh_string *lsh_hash = ssh_format("%lfxS", |
| + hash_string(&crypto_md5_algorithm, |
| + PUBLIC_KEY(v), 1)); |
| + uint32_t keysize = KEY_SIZE(v); |
| + |
| + switch (method) |
| + { |
| + case ATOM_SSH_DSS: |
| + case ATOM_DSA: |
| + keytype = "DSA"; |
| + break; |
| + case ATOM_SSH_RSA: |
| + case ATOM_RSA_PKCS1_SHA1: |
| + case ATOM_RSA_PKCS1_MD5: |
| + case ATOM_RSA_PKCS1: |
| + keytype = "RSA"; |
| + break; |
| + default: |
| + werror("Unrecognized key type"); |
| + return -1; |
| + } |
| + |
| + for (pp = paths; *pp && ret <= 0; pp++) { |
| + struct lsh_string *blacklist_file = ssh_format("%lz.%lz-%di", |
| + *pp, keytype, keysize); |
| + int r = blacklisted_key_in_file(lsh_hash, blacklist_file); |
| + lsh_string_free(blacklist_file); |
| + if (r > ret) ret = r; |
| + } |
| + |
| + if (ret > 0) { |
| + werror("Key is compromised: %z %i %fS\n", keytype, keysize, |
| + lsh_string_colonize(lsh_hash, 2, 0)); |
| + } else if (ret < 0) { |
| + verbose("No blacklist for key type %z size %i", keytype, keysize); |
| + } |
| + return ret; |
| +} |
| --- a/src/dsa.c |
| +++ b/src/dsa.c |
| @@ -187,6 +187,14 @@ do_dsa_public_spki_key(struct verifier * |
| "y", self->key.y); |
| } |
| |
| +static uint32_t |
| +do_dsa_key_size(struct verifier *v) |
| +{ |
| + CAST(dsa_verifier, self, v); |
| + |
| + return mpz_sizeinbase(self->key.p, 2); |
| +} |
| + |
| static void |
| init_dsa_verifier(struct dsa_verifier *self) |
| { |
| @@ -197,6 +205,7 @@ init_dsa_verifier(struct dsa_verifier *s |
| self->super.verify = do_dsa_verify; |
| self->super.public_spki_key = do_dsa_public_spki_key; |
| self->super.public_key = do_dsa_public_key; |
| + self->super.key_size = do_dsa_key_size; |
| } |
| |
| |
| --- a/src/lsh-decode-key.c |
| +++ b/src/lsh-decode-key.c |
| @@ -133,6 +133,10 @@ lsh_decode_key(struct lsh_string *conten |
| werror("Invalid dsa key.\n"); |
| return NULL; |
| } |
| + else if (blacklisted_key(v, type) > 0) |
| + { |
| + return NULL; |
| + } |
| else |
| return PUBLIC_SPKI_KEY(v, 1); |
| } |
| @@ -150,6 +154,10 @@ lsh_decode_key(struct lsh_string *conten |
| werror("Invalid rsa key.\n"); |
| return NULL; |
| } |
| + else if (blacklisted_key(v, type) > 0) |
| + { |
| + return NULL; |
| + } |
| else |
| return PUBLIC_SPKI_KEY(v, 1); |
| } |
| --- a/src/lsh-writekey.c |
| +++ b/src/lsh-writekey.c |
| @@ -397,14 +397,18 @@ process_public(const struct lsh_string * |
| { |
| struct signer *s; |
| struct verifier *v; |
| + int algorithm_name; |
| |
| - s = spki_make_signer(options->signature_algorithms, key, NULL); |
| + s = spki_make_signer(options->signature_algorithms, key, &algorithm_name); |
| |
| if (!s) |
| return NULL; |
| |
| v = SIGNER_GET_VERIFIER(s); |
| assert(v); |
| + if (blacklisted_key(v, algorithm_name) > 0) { |
| + return NULL; |
| + } |
| |
| return PUBLIC_SPKI_KEY(v, 1); |
| } |
| @@ -416,7 +420,8 @@ main(int argc, char **argv) |
| int private_fd; |
| int public_fd; |
| struct lsh_string *input; |
| - struct lsh_string *output; |
| + struct lsh_string *priv_output; |
| + struct lsh_string *pub_output; |
| const struct exception *e; |
| |
| argp_parse(&main_argp, argc, argv, 0, NULL, options); |
| @@ -439,16 +444,22 @@ main(int argc, char **argv) |
| return EXIT_FAILURE; |
| } |
| |
| - output = process_private(input, options); |
| - if (!output) |
| + pub_output = process_public(input, options); |
| + if (!pub_output) |
| + return EXIT_FAILURE; |
| + |
| + priv_output = process_private(input, options); |
| + if (!priv_output) |
| return EXIT_FAILURE; |
| |
| + lsh_string_free(input); |
| + |
| private_fd = open_file(options->private_file); |
| if (private_fd < 0) |
| return EXIT_FAILURE; |
| |
| - e = write_raw(private_fd, STRING_LD(output)); |
| - lsh_string_free(output); |
| + e = write_raw(private_fd, STRING_LD(priv_output)); |
| + lsh_string_free(priv_output); |
| |
| if (e) |
| { |
| @@ -457,18 +468,12 @@ main(int argc, char **argv) |
| return EXIT_FAILURE; |
| } |
| |
| - output = process_public(input, options); |
| - lsh_string_free(input); |
| - |
| - if (!output) |
| - return EXIT_FAILURE; |
| - |
| public_fd = open_file(options->public_file); |
| if (public_fd < 0) |
| return EXIT_FAILURE; |
| |
| - e = write_raw(public_fd, STRING_LD(output)); |
| - lsh_string_free(output); |
| + e = write_raw(public_fd, STRING_LD(pub_output)); |
| + lsh_string_free(pub_output); |
| |
| if (e) |
| { |
| --- a/src/publickey_crypto.h |
| +++ b/src/publickey_crypto.h |
| @@ -203,5 +203,7 @@ parse_ssh_dss_public(struct simple_buffe |
| struct verifier * |
| make_ssh_dss_verifier(const struct lsh_string *public); |
| |
| +int |
| +blacklisted_key(struct verifier *v, int method); |
| |
| #endif /* LSH_PUBLICKEY_CRYPTO_H_INCLUDED */ |
| --- a/src/rsa.c |
| +++ b/src/rsa.c |
| @@ -167,6 +167,14 @@ do_rsa_public_spki_key(struct verifier * |
| self->key.n, self->key.e); |
| } |
| |
| +static uint32_t |
| +do_rsa_key_size(struct verifier *v) |
| +{ |
| + CAST(rsa_verifier, self, v); |
| + |
| + return mpz_sizeinbase(self->key.n, 2); |
| +} |
| + |
| |
| /* NOTE: To initialize an rsa verifier, one must |
| * |
| @@ -184,6 +192,7 @@ init_rsa_verifier(struct rsa_verifier *s |
| self->super.verify = do_rsa_verify; |
| self->super.public_key = do_rsa_public_key; |
| self->super.public_spki_key = do_rsa_public_spki_key; |
| + self->super.key_size = do_rsa_key_size; |
| } |
| |
| /* Alternative constructor using a key of type ssh-rsa, when the atom |
| --- a/src/server_authorization.c |
| +++ b/src/server_authorization.c |
| @@ -93,7 +93,8 @@ do_key_lookup(struct lookup_verifier *c, |
| PUBLIC_SPKI_KEY(v, 0), |
| 1)); |
| |
| - if (USER_FILE_EXISTS(keyholder, filename, 1)) |
| + if (USER_FILE_EXISTS(keyholder, filename, 1) |
| + && blacklisted_key(v, method) < 1) |
| return v; |
| |
| return NULL; |
| Property changes: |
|---|
| Added: svn:executable |
|---|
| ## -0,0 +1 ## |
|---|
| +* |
|---|
| \ No newline at end of property |
|---|